class_docstr: Rule class to handle processing
code: def rule_names(cls):
      return list(Rule._rules.keys())
  
imports: import ast
  from copy import deepcopy
  import hashlib
  import inspect
  import json
  from streamalert.shared.logger import get_logger
label_desc: Use image node_id 16 for calling the Rule obj's underlying member method code with example usage: obj.rule_names(cls) and returns: list